The invention relates to drive units and more particularly to internal combustion engines having a waste heat turbine unit operated by the exhaust gases of the internal combustion engine, wherein the energy contents of the exhaust gas are utilized. The invention is particularly well suited for automotive vehicles.
In a conventional drive unit (German Pat. No. 27 57 236) of the type of construction described above, it has been discovered by testing, that utilization of the energy contents in the exhaust gases of the internal combustion engine is basically possible. However, it seems that the type of waste heat turbine unit, the feeding of the medium, its conversion to steam, and, finally, the exploitation of the steam for ensuring a high degree of efficiency can be optimized.
Therefore, it is an object of the invention to improve this drive unit in such a way that it is safe in operation and yields a high degree of efficiency with the use of readily producible structural components.
According to the invention, in a drive unit including an internal combustion engine and a waste heat turbine unit operated by the exhaust gases of the internal combustion engine for utilizing the energy from the exhaust gases, a waste heat turbine unit is provided. The waste heat turbine unit compries a cylinder member having an exterior and a hollow interior. Blading is provided which is exposed to the exhaust gases and is carried on the exterior of the cylinder member. A steam turbine unit is provided along with means for supplying a liquid medium, convertible into steam, to the interior of the cylinder member. The liquid medium is expandable in the steam turbine unit for generating power.
The advantages primarily attainable by the invention are to be seen in that the waste heat turbine unit operates at a relatively high degree of efficiency and is a compact assembly wherein utilization of the energies contained in the exhaust gas are readily realizable. On account of the blading of the rotating cylinder, a relatively large surface area is provided which, besides yielding satisfactory heat transfer values, is important for the transmissible heat flow. As a consequence, a favorable weight-to-surface ratio of the cylinder is obtained. By the instant invention's manner for feeding the liquid medium to the inner wall of the cylinder, film evaporation is attained, accompanied by a high heat transfer coefficient and good cooling of the cylinder. Also, the temperature level is maintained low by this feature, so that high temperature-resistant turbine materials need not be used. The cylinder can be made of an aluminum alloy.
The housing, (which, with an appropriate internal coating, can also be made of an aluminum alloy,) the cylinder, and the steam turbine unit are components that can be manufactured without any problems. Also, they can be dimensioned in size and arranged spatially with respect to one another in such a way that the waste heat turbine unit represents a compact module which can be attached to the internal combustion engine in a simple way.
The blading exposed to the exhaust gases is provided merely in the zone of the exhaust gas inlet which can be easily put into practice from the viewpoint of manufacturing technique, and contributes toward weight reduction. A satisfactory driving function of the cylinder is obtained by arranging the blading on two spaced-apart wheel rims and having these exposed to tangential flow. These wheel rims can either be produced integrally with the cylinders or can also be formed by separate components.
A satisfactory feeding of the liquid medium is effected via the atomizer nozzles and the centrifugal pump. The latter can be intergrated into the cylinder in a simple way.
The superheater provided within the cylinder enhances the high degree of efficiency of the steam turbine unit. The use of the oppositely rotating turbine wheels and their structure ensures satisfactory operation of the steam turbine unit.
By connecting a mixture condenser installed in the housing downstream of the steam turbine unit, an additional condenser can be eliminated.
Preheating of the conduit leading to the device by means of the exhaust gases likewise contributes toward optimizing of the operation.
Finally, the control device ensures safe and effective operation of the waste heat turbine unit.
Further objects, features and advantages of the present invention will become more apparent from the following description when taken with the accompanying drawings which show, for purposes of illustration only, embodiments in accordance with the present invention.